Taking to Instagram, McMillan—the brains behind 'The Rachel'—described the rare beauty move as an "honour to be a part of" on Instagram.
"The hair is Jen's natural curl and waves," he confirmed in the caption, alongside a photograph of the former Friends star flexing her chameleon-like abilities at the premiere.
Thankfully, McMillan then went on to detail how to recreate the headline-worthy look at home so grab a pen.
Those with natural waves will be pleased to learn that all you need to do is leave your hair to air dry before touching up some pieces at the root with Dyson's Supersonic Blow Dryer.
In order to create a more polished curl, weave the ghd Classic Wave Wand through your hair before finishing with a detangling spray.
McMillan says he finished the look by layering products on, including Drunk Elephant’s tangle spray.
The product described as a “weightless leave-in mist that detangles, smoothes, and provides heat protection while restoring natural movement, manageability, and shine.”
Add a smothering of leave-in conditioner for a shine Hollywood is sure to approve of.